Lubricating oil composition



Patented Sept. 15, 1953 LUBRICATING 01L COMPOSITION Donald S. Melstrom and Forrest J. Watson, Oakland, Calih, asslgnors to Shell Development Company, San Francisc of Delaware 0, CaliL, a corporation No Drawing. Application June 21,1949,

Serial No. 100,544

with the susceptibility of viscosity to temperature changes. Such an evaluation is usually made with reference to the viscosity index scale advanced by Dean and Davis. The viscosity index figures which follow hereinafter refer to this scale which is well known in the art. According to this scale, the viscosity of an oil is determined at 100 F. and 210 F. in Saybolt Universal seconds.

' If an oil has a low viscosity index, the viscosity changes rapidly with temperature while a high viscosity index indicates relative insensitivity to thermal influences.

The addition of extraneous compounds to lubricating oils to improve their viscosity temperature relationship is a well developed art. A'number of polymeric compounds of simple hydrocarbons have been utilized for this purpose, such as polyisobutylene. A second type of polymeric material found to be of use for improvement in viscosity index includes polymers of esterifled methacrylic acid. While each of these types of materials is effective to a certain extent, they exhibit shortcomings which appear to be inherent in their chemical structure. The isobutylene polymers, for example, are subject to depolymerization when an oil containing them is used for a period of time at high engine operating temperatures. It appears that differences in molecular structure are a determining feature in the relative solubility, effectiveness and stability as a viscosity improving agent in lubricating oils.

It is an object of the present invention to provide improved lubricating compositions. It is a further object of this invention to provide lubricating compositions having improved viscosity temperature relationships. It is a special object of this invention to provide lubricating compositions particularly suitable for use in friction drive torque converters. Other objects will become apparent hereinafter.

Now, in accordance with this invention, it has been found that polymeric alkylene sulfones have exceptional properties for improving the viscosity and viscosity index of lubricants. Still in accordance with this invention, it has been discovered that the polymeric alkylene sulfones having from 11 Claims. (Cl- 25.2-48.2)

between the sulfone groups.

. and branched-chain isomers.

2 2 to 4 carbon atoms between sulfone groups and having an alkyl side chain of 5 to 16 carbon atoms directly attached to one of the carbon atoms separating the sulfone groups are especial ly desirable because of a particularly unique modified dilatancy in mineral oils. Again in accordance with the present invention, the latter polymeric sulfones when compounded with mineral lubricating oils are particularlyuseful as the lubricant in friction gear torque converters.

The polymeric sulfones with which the present invention is concerned may be prepared by several alternative methods. Polymeric alkylene sulfones having 2 or 4 carbon atoms between sulfone groups are readily prepared by action of sulfur dioxide at low temperatures on monoolefins or conjugated diolefins. A general description of the preparation of typical sulfones included in this group is to be found in a paper by R. D. Snow and F. E. Frey, Journal of Industrial and Engineering Chemistry, vol. 30, 1938, pages 176-182. A second variety of polymeric alkylene sulfone is that containing at least 5 carbon atoms Materials of this description are disclosed in United States Patent 2,201,884 to W. H. Carothers. sulfones of this latter group are prepared by oxidation of polymeric alkylene sulfides. A particularly desirable group of polymers for use in the present invention comprises the copolymers of sulfur dioxide with alpha-olefinic hydrocarbons having from 7 to 24 carbon atoms. Olefins derived from the cracking of paraffin wax, referred to as cracked wax olefins may be used inthe preparation of the sub ject polymers Thes include,for example, the alpha varieties of heptene, decene, dodecene, tetradecene and octadecene, including both normal Copolymerization of this type of alpha-olefin with sulfur dioxide results in the formation of high molecular weight polymeric materials having 2carbon atoms between sulfone groups, one of the carbon atoms having an alkyl substituent which preferably may varybetween 5 and 16 carbon atoms in length. The reason for this preference in structure lies in the fact that polymers of this variety exhibit an unusual variety of dilatancy when dispersed in mineral lubricating oils. An ordinary dilatant fluid is one which thickens when subjected to shear and which immediately regains its normal fluidity when the shearing force is removed. In the present instance, it has been found that mineral oils containing polyalkylene sulfones of the above preferred description exhibit increased thickening when subjected to agitation 0r stirring phosphate. 1phates"may be used as well, such as diphenyl bricating or preventing wear, a "of'oil *be-' tween the friction gear surfaces usually results in increased slippage betweenthecontact points of the surfaces of the engaging qgears. Hence, the dilatant properties of the present compositions find ready application in the..lubrication of friction gears. When forceis applied .to the gears lubricated with these compositions, the gell ing action which results materially reduces the slippage to which ordinary lubricants are subjected;

r-Anoth'er property which makes these new compositions especially useful for friction gear lubrication is the mild extreme pressure characterelStiCS which a-ppear to be due to-the presence of the rsulfone groups in the polymeric additives. It :has :been :found that lubricating compositions containing .small percentages of polymeric alkylenesulfones have maximum seizure load ratings approximately 30% greater than the unmodifieddubricating oils. This property adds to the value -.of thecompositions, especially in their use as torque converter fluids.

fI-hedubricants in which the polyalkylene sulfones may. .be employed include especially min- .eral lubricating oilsan'dalso esters of dicarbox- .yli'c acids, .such as bis(.2-ethylhexyl) sebacate. Anothertgeneral class ofsynthetic lubricant use- '.ful :as base lubricant .in compositions of this .invention'comprises-alkylene oxideepolymers which 'may bepreparedfrom alkylene .epoxides'or alkylenetglycols. A particularly useful variety of this -.type includes .the polymers of .trimethylene :glycobor of rpropyleneoxide. Other well known 4 sulfones are present in an amount between 0.5% and 5.0%, by weight, based on the weight of the lubricating oil. Other ingredients may be present in the composition such as standard anti-oxidants, extreme pressure additives, additional vie- .cosity index improvers, anti-corrosion agents, and similar materials all as well known in the art. Greases may be prepared containing the "polymeric alkylene sulfones and containing the well known grease-forming soaps or the more recently developed inorganic gel greases prepared -.by.-th e use of :silica gel, alumina gel and .gelsof other inorganic polyvalent metal oxides.

The preferred process as referred to above for the preparation of sulfones useful in the ,present compositions comprises addition of alpha- I ol'e'fins to an excess of liquid sulfur dioxide at reflux temperature (-l0 C.) in the presence of a 'catalyst such as peroxides or nitrates. The

reaction mixture is stirred at reflux for approximatelyone-half hour in .the presence or absence of .inert-diluents such as dioxane and the .like. The reaction mixture is thenpermitted to warm to room temperature so as to evaporate unreacted materials. In the'case ofa highermolecular weight alpha-olefin such as octadecene-I, the reaction may be conducted under pressure at room temperature soas to permit liquefication of the hydrocarbon. .Ithas been noted that the polymerizationreaction proceeds at a negliblyslow rate if eitherof the reactants .is solid. On the other hand, no polymerization appears to occur when the reactantsare in a vaporized condition. With these two limitations in mind, a variety of temperatures and pressuresmay be chosen to maintain the reactants in a liquefied state with a minimum vapor phase present. Ordinarily, this will mean that the temperatures will be between about -20 C. and +30 .C., although these temperatures may be increased in either direction with corresponding change inpressure. The following table illustrates'conditions under which representative polymericsulfones of normalolefins maybe prepared.

Analysis of Polymer .iM "OlefliiicComgg} g additional Catalyst or 932 3 Found ryforwdnznson pound Con? :Sclvent IlJl'llbltOI .Pement pmmd Per- 52%; Per- Percent Percent Percent cent 0 H cent S 'H .S

.i 'retrsdecenem 0:25 300 'dioxan'c, 02511101-. Peroxide '92 63.98 10. 32 11,3 4. lliDod'ecnec 0125' 250 dioxaue, 0.4511101" 05 g.{PNB' '79 :62. 22 10. 42 13.3 62.01 10. 41 13.8 .1;Deceue .05 250 dioxane, 02511101.. 1 g.-%il1 TO3 111 86 58. 09, 9.95 15.4 58. 79 9. 87 15:7

co 0 r '11;Bgpe1i -io:5 I250 e "do Peroxide 88, 50.99 f8. 61' 19.5 51.82 8.70 953 .1-Octadecene one 20. none 2 :32. ale. 94 69.36 11.67 9.05 68.30 11.47 10,

" T'NB' is l,3,5-trinit'robenzene, aninhibitor. lleaction was carriedout in a sealed tube at room temperature.

synthetic'and'natur'al 'lubricants may be used in the present compositions, such as vegetable oils '-'such'as=castor oil, "fish and animal oils, organic phosphates and chlorinated hydrocarbons exempli'fied by hexachlorobutadiene and tricresyl Mixed phosphates or alkyl phos- 'o'ctyl phosphate, trioctyl phosphate or 'tributyl phosphate.

In order tobe effective for the improvement in viscosity index,'the polymeric alkylene sul- "fon'es shouldfbe; present in' an amoun'tfr'om about .Due :to the insolubility of the polymeric .alkylene "sulfones in the solvents normally em aployed for vmolecular weight determinations, there has been no accurate-method developed for estimating the chain length of the polymers described above. Evidence indicates, however, that the polymers have molecular-weightsggenerally ranging between about 5,000 and 100,000. :Due to the extremely high molecular weights of these substances, the identity of 'end groups of the linear polymers are substantially imma- "terial;.particularly as' totheir utility in the pres- 031%*to-about*l0.0% by weight. -Preferably, the '75 entiinvention; Up to'th'e presenttime, no analyses of the end group structures have been made. It is believed that at least one of the end groups is in the form of a sulfone group or of a hydroxyl, but neither of these proposals has been firmly established.

In order to illustrate the effect of adding a sulfone to a lubricating oil, the following comparison was made: A given mineral lubricating oil was found to have a viscosity index of 53, with a viscosity at 100 F. of 10.6 centistokes and 2.5 centistokes at 210 F. Upon the addition of 1% by weight of a polymeric octadecene sulfone produced by copolymerization of sulfur dioxide and octadecene-l at room temperature under pressure, the viscosity index increased to 135, the composition having a. viscosity of 18.5 centistokes at 100 F. and 4.0 centistokes at 210 F.

When a mineral lubricating oil is modified by the addition of 0.75% of a polymeric tetradecene sulfone, prepared from tetradecene-l as described in the above table, the viscosity index is raised from 50 to 96. The addition of 1.5% of a polymeric octene-l sulfone to the same mineral oil gives a composition having a viscosity index of 116.

The claimed invention is:

1. A lubricant comprising a hydrocarbon lubricating oil base and in admixture therewith a minor amount sufllcient to improve the viscosity index of the oil of a copolymer of cracked wax olefins and sulfur dioxide having a molecular weight between about 5000 and 100,000.

2. A lubricating composition comprising a lubricating oil base and in admixture therewith a minor amount sufficient to improve the viscosity index of the oil of a polyalkylene polysulfone each sulfone group being separated by at least 5 carbon atoms, said polysulfone being prepared by oxidation of polymeric alkylene sulfides.

3. A lubricant comprising a hydrocarbon lubricating oil base and in admixture therewith a minor amount sufficient to improve the viscosity index of the oil of a copolymer of cracked wax alpha olefins and sulfur dioxide.

4. A lubricant comprising a hydrocarbon lubricating oil base and in admixture therewith a minor amount sufiicient to improve the viscosity index of the oil of a copolymer of cracked wax alpha monoolefins and sulfur dioxide.

5. A lubricating composition comprising a lubricating oil base and in admixture therewith from 0.1% to by weight of a polyalkylene polysulfone prepared from olefins having from 7 to 24 carbon atoms per molecule and said polysulfone being prepared by polymerization of alpha-olefins and sulfur dioxide.

index of the oil of a polyalkylene polysulfone hava ing a molecular weight from. about 5,000 to about 100,000 prepared from olefins having from 7 to 24 carbon atoms per molecule said polysulfone being prepared by copolymerization of alpha olefinsand sulfur dioxide.

7. A lubricating oil composition exhibiting improved dilatancy comprising a major amount of a mineral lubricating oil base and 0.1 to 10% by weight of a poly(alkylene- ,2 sulfone) having a molecular weight between 5,000 and 100,000, the sulf-one groups of which are separated by 2 to 4 carbon atoms, one of which bears an alkyl substituent of 5 to 16 carbon atoms said sulfone being prepared by copolymerization of alpha olefins and sulfur dioxide.

8. A lubricant comprising a hydrocarbon lubrieating oil base and in admixture therein a minor amount sufficient to improve the viscosity index of a polysulfone prepared by the polymerization of n-octadecene-l and S02.

9. A lubricant comprising a hydrocarbon lubricating oil base and in admixture therewith a minor amount sufiicient to improve the viscosity index of the oil of a polysulfone prepared by the polymerization of a normal l-alkene having from 12 to 20 carbon atoms and S02.

10. The process for the lubricating of metallic surfaces which comprises maintaining thereon a lubricating oil composition comprising a hydrocarbon lubricating oil base in admixture therewith a minor amount suflicient to improve the viscosity index of the oil of a polysulfone prepared by the polymerization of a normal l-alkene having from 12-20 carbon atoms and sulfur di- References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,452,946 Weiss Apr. 24, 1923 2,201,884 Carothers May 21, 1940 2,225,266 Frey Dec. 17, 1940 2,483,499 Lieber et a1. Oct. 4, 1949 

1. A LUBRICANT COMPRISING A HYDROCARBON LUBRICATING OIL BASE AND IN ADMIXTURE THEREWITH A MINOR AMOUNT SUFFICIENT TO IMPROVE THE VISOSITY INDEX OF THE OIL OF A COPOLYMER OF CRACKED WAX OLEFINS AND SURFCE DIOXIDE HAVING A MOLECULAR WEIGHT BETWEEN ABOUT 5000 AND 100,000. 